Customizable Auto-Off
All of the flashes turn off automatically after a few minutes of inactivity, and can be turned back on by lightly pressing the camera's shutter button. This auto-off feature can be disabled on the Pentax AF540FGZ, and on the higher-end Metz flashes (48 AF-1 and up) can either be disabled or changed between a 1 minute or 10 minute delay.
This can be very important when using the flash as a remote slave, where having the flash go to sleep automatically can be quite annoying.